September 2011 - OpenBSC - lists.osmocom.org

GPRS - local and foreign TLLIs
by Luca Melette 04 Feb '26

04 Feb '26

Hello everybody, after setting up a nanoBTS with OpenBSC/SGSN/GGSN, I had some troubles trying to connect my smartphone to the GPRS cell. Investigating the BTS-to-SGSN traffic, I saw that the frames sent by the SGSN were all marked with the same N(U) value (at LLC layer), the value was 0. With some debug, I found that the there was a mismatch in the TLLI storage, used to keep the status of attached terminals. The mentioned code is contained in gprs_llc.c, involving LL Entity functions and gprs_llc_tx_ui(). /* look-up or create the LL Entity for this (TLLI, SAPI) tuple */ lle = lle_by_tlli_sapi(msgb_tlli(msg), sapi); if (!lle) { struct gprs_llc_llme *llme; LOGP(DLLC, LOGL_ERROR, "LLC TX: unknown TLLI 0x%08x, " "creating LLME on the fly\n", msgb_tlli(msg)); llme = llme_alloc(msgb_tlli(msg)); lle = &llme->lle[sapi]; } The TX function uses the previously received TLLI to lookup for the LLE. The lle_by_tlli_sapi() performs the search, but preliminary it applies a foreign2local TLLI conversion to ensure to have a local one. Since no valid entry for the searched TLLI is found, a new one is created. And the problem is here. The new entry has the foreign TLLI. Next time the lookup fails again, and a new entry is created. This way, the counter N(U) is always reset, and the mobile do not recognize the message sequence and no attach is possible. My question is about foreign and local TLLIs. I patched the lookup, avoiding the conversion, so that the LLE is found and everything works fine... but... What is the sense of the conversion? Should the TLLI be always stored as a local one? Can this problem be solved with another foreign2local while allocating new entries? Actually, my problem has been solved with that workaround. But I'm curious to know what is the right way. Hope somebody can answer :) Thanks. Cheers, LM

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Re: Help with sccp library
by mosbah abdelkader 07 Jul '25

07 Jul '25

> I don't understand. This callback will be called with data you need to write > to the network. In case of MTP Level3 you will need to wrap that around the > msgb you got. I means: is the interaction with mtp3 layer implemented (is sending sccp data by mtp3 implemented by the library?)? Also, what about the reception of data from mtp3 layer. is that implemented in the sccp lib. I am asking these questions because I see the code of mtp3 in the lib but no significant call is present in the sccp part of the lib. Thank you for your help.

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Several questions
by jason mercury 06 Dec '12

06 Dec '12

I have some questions: 1) When I start bsc_hack bsc_init.c first establishes OML link and initializes the bts then it establishes RSL link and bts starts broadcasting. However, it takes so much time to start the bts. Instead of this I want to do the following: it establishes OML link at the beginning and only once, then when i want to start broadcasting it establishes just the RSL link and bts will start faster since i don't have to wait for OML link. What should be done for this? 2) If i send one or two word messages from telnet interface it is okay. But if i send a longer message the phone could't receive the end of the message correctly(last words may be incomplete). Did any one encounter with this problem? What is wrong with me? 3) Could I send SMS in which extension of the sender is text not integer. For example, i want to send an information SMS that this is a test network. For this purpose i want to send an SMS from 'OpenBSC'. I set the extension of the first subscriber in database as text and tried to send the SMS but SMS wasn't delivered. What should i do? 4) Can i add SMS externally to SMS table of database? Thanks. Jason

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[PATCH 0/3] rb-tree based timer infrastructure for libosmocore
by pablo＠gnumonks.org 18 Oct '11

18 Oct '11

From: Pablo Neira Ayuso <pablo(a)gnumonks.org> Hi! This patch reworks the timer insfrastructure of libosmocore to make it more scalable. I remember some discussion with Harald while I was in Berlin that this can be of interest. It also reworks the timer torture test, the current list-based timer seems to have problem with it. You can find this changes in the pablo/timer branch. Pablo Neira Ayuso (3): add rb-tree implementation to libosmocore timer: add scalable RB-tree based timer infrastructure tests: add new torture test for timer infrastructure include/osmocom/core/Makefile.am | 2 +- include/osmocom/core/linuxrbtree.h | 160 +++++++++++++++ include/osmocom/core/timer.h | 6 +- src/Makefile.am | 2 +- src/rbtree.c | 389 ++++++++++++++++++++++++++++++++++++ src/timer.c | 176 +++++++++-------- tests/timer/timer_test.c | 141 ++++++++++--- 7 files changed, 757 insertions(+), 119 deletions(-) create mode 100644 include/osmocom/core/linuxrbtree.h create mode 100644 src/rbtree.c -- 1.7.2.5

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GPRS not coming up on NanoBTS 140
by Gus Bourg 15 Oct '11

15 Oct '11

Hello all, Looking for ideas. I have a NanoBTS Model 140 which doesn't seem to work with GPRS. It never connects to the SGSN. The openbsc/sgsn environment is ok - I can swap in another nano and it works fine. I've taken some log captures:

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[RFC] proposal for new library: libosmo-net
by Pablo Neira Ayuso 30 Sep '11

30 Sep '11

Hi, After some private discussion with Harald, I'd like to propose one new library to abstract the network interface that is used to communicate two elements that are part of one GSM network (no matter if it's on the A-bis interface, A interface, ...). This new library, whose proposed name can be "libosmo-net", would initially support: - E1 interfaces. - Ethernet + IPA TCP/IP. - rs232 (as required by bs11 its config interface). This support is included in libosmo-abis, so my idea is to extract this code from it and leave in libosmo-abis only the specific A-bis bits. The libosmo-net library would be extensible, so we can add new interfaces to it (new E1 cards supported, new protocols over BSD sockets, and so on). The interface provided to the client of the library will be homogeneous for all supported interfaces (at least, as much as we can). The new library will provide: * a constructor/destructor to create/release some network interface of * a given supported type. * a call-back for receiving incoming messages that will take the actual msgb. * one function for sending signalling messages. As well as many helper functions in this regard. Therefore, libosmo-abis will require this new libosmo-net library after all is done. For the A interface, I'd propose some hypothetical libosmo-a library that will contain the specific A interface protocols. Let me know what you think.

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comments on jolly/lapd branch
by Harald Welte 25 Sep '11

25 Sep '11

Hi Andreas, I've done a quick read through your jolly/lapd branches, and I have the following comments: 1) great work, thanks :) 2) lapd_profile I would like to use a 'struct lapd_profile' instead of a simple enum. Why? Because this puts all the values/parameters (like k, n201, short_address, use_sabme, t200, etc.) into the control of the caller, instead of the library. so basically we would have struct lapd_profile { uint8_t k; unsigned int n201; ... }; and then some library-pre-defined ones: const struct lapd_profile lapd_profile_isdn = { ... }; const struct lapd_profile lapd_profile_abis = { ... }; but this way an application could define their own profile with slightly different timers, without having to modify the library codebase. The actual lapd_datalink then just would have a const struct lapd_profile *profile; member that is assigned during lapd_dl_init(). 3) the msgb_free() changes in input/dahdi.c, src/e1_input.c, etc. should be a separate patch, as they are actual bugfixes of the old code, as far as I understand. That bugfix patch should be first, then the actual LAPD restructuring on top of it. 4) regarding the two-dimensional switch() statements, I suggest introducing the following macros to include/osmocom/core/osmo_prim.h: #define OSMO_PRIM(prim, op) (prim << 8 | op & 0xFF) #define OSMO_PRIM_HDR(oph) OSMO_PRIM(oph->primitive, oph->operation) then you can do something like this in the lapd code: switch (OSMO_PRIM_HDR(oph)) { case OSMO_PRIM(PRIM_DL_EST, PRIM_OP_REQUEST): ... } Regards, Harald -- - Harald Welte <laforge(a)gnumonks.org> http://laforge.gnumonks.org/ ============================================================================ "Privacy in residential applications is a desirable marketing option." (ETSI EN 300 175-7 Ch. A6)

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New open hardware for OpenBTS
by Alexander Chemeris 21 Sep '11

21 Sep '11

Hi all, (and sorry to those who receive this twice) At Sept 15th I will speak at the Open Hardware Summit at the breakout session "Open Hardware in Voice Telecommunications" and there I will present Fairwaves project to create an open hardware transceiver for OpenBTS. Someone may recall I proposed similar project about 1.5 years ago, but then abandoned due to lack of interest from the community. Now it was revived on a new level, thanks to financial and motivational support from Jean-Samuel Najnudel of BJT Partners SARL. As an experiment this project will be completely open-sourced in an open-source hardware way. Project is in active development, so just to give you an idea of what we're aiming: * Targeted for rural installations. * CAPEX and OPEX optimized. * 2 TRX per sector. Each TRX connected to its own antenna with its own saturated (=cheap) power amplifier on Tx side. On Rx side both antennas are used to provide diversity receive. * Reference clock synchronized to GPS for accurate timing. * Based on USRP N200, but with Xilinx Spartan 6 and LimeMicro LMS6002D. Which means it's actually design is much more capable then just GSM. More details, web-site, schematics, etc will be available after OHS. First samples of the hardware we hope to have at the end of this year. If you're going to OHS - come to our breakout session to discuss the project and share your ideas! -- Regards, Alexander Chemeris.

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[PATCH/RFC 0/2] libosmo-abis ctrl related fixes
by Daniel Willmann 19 Sep '11

19 Sep '11

Hello, attached are two patches I came across while looking at the pablo/ctrl-updates branch in OpenBSC. The first one is just a bugfix for a resource leak and the second one adds a possibility to register a callback that will notify you if the connection is lost. This is needed for the control interface as we'll need to clean up some ctrlif related things if a connection is lost. Be aware that I haven't tested this with the ctrl-updates branch since this doesn't compile yet. I did test that master still compiles and osmo-bsc/nat don't segfault on start (though openbsc doesn't seem to use ipa_server_conn at the moment). The e1inp_ipa_{bsc,bts}_test worked as well. Regards, Daniel Willmann (2): ipa: Fix resource leak if we encounter an error in ipa_server_conn_read ipa: Add a callback to detect if the server_conn was closed include/osmocom/abis/ipa.h | 3 ++- src/input/ipa.c | 6 +++++- src/ipa_proxy.c | 2 +- 3 files changed, 8 insertions(+), 3 deletions(-) -- 1.7.6.1

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bug in A-bis OML wireshark dissector
by Pablo Neira Ayuso 19 Sep '11

19 Sep '11

Hi! While submitting the A-bis OML wireshark dissector I noticed one bug in it that results in bogus message labeling. The following patch should be applied to osmocom/wireshark.git tree. P.S: I have submitted a patch to wireshark bugzilla that includes this bugfix.

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